The present invention relates to an ultrasonic transmitter and receiver for vehicles and, more particularly, to an ultrasonic wave transmitter and receiver adapted to transmit an ultrasonic wave and to receive the echo reflected by an obstruction at the rear side of a vehicle to detect the distance between the vehicle and the obstruction.
In the known device of the kind mentioned above, an ultrasonic transducer is mounted in the vicinity of the rear bumper of the vehicle. In this known device, the vibration of the ultrasonic transducer at the time of the transmission of ultrasonic pulses remains as an attenuated oscillation even in the beginning period of receiving of the echo. Since the ultrasonic transducer is mounted in the vicinity of the bumper as stated above, it is difficult to discriminate the echo signal reflected by the obstruction from the wave of the above-mentioned attenuated oscillation. In consequence, it is quite difficult to detect the distance between the rear bumper and the backward obstruction close to the bumper in which the driver is most interested during reversing of the vehicle.